Stirrers or food processors commonly available on the market comprise blade assembly with only a single layer of stirring blades. Although several kinds of food processors are provided with two or three layers of stirring blades, each layer is consisted of stirring blades of the same shape or similar shapes, and most of the blades cannot be disconnected with each other. Therefore these blades can not be combined in various ways, which limits the kind of foods that the processor can process.